Boom limit safety device



June 18, 1963 c. w. GALUsKA 3,094,221

BOOM LIMIT SAFETY DEVICE Filed May 51, 1962 2 Sheets-Sheet 1 Fig./

BY @w25-M June 18, 1963 1 c. w. GALUsKA 3,094,221

BOOM LIMIT SAFETY DEVICE Filed May 31, 1962 2 Sheets-Sheet 2 5 Char/es W Ga/uska /8 INVENTOR.

98 @zum BY MW *f/fzaw United States Patent O 3,094,221 BOOM LIMIT SAFETY DEVICE Charles W. Galuska, San Jose, Calif., assignor of fifty percent to Lois Edwards, San Jose, Calif.

Filed May 31, 1962, Ser. No. 199,152 4 Claims. (Cl. 212-39) This invention relates to a novel and useful boom limit safety device and more specifically to a safety device which is adapted to be used on cranes provided with pivoted booms.

Most cranes which are provided with pivoted booms utilize winding drums for raising and lowering the free end of the boom by means of -a tension member which is Wound about the winding drum and attached to the free end of the boom.

The main object of this invention is to provide a limit stop for the boom of a crane which Will -be capable of sensing when the boom of a crane approaches a substantially vertical position when being raised in order that means may be provided for preventing the free end of the boom from swinging upwardly past a vertical plane in which the axis of rotation of the boom is contained.

Another object of this invention is to provide a means whereby a clutch mechanism utilized to drivingly connect a prime mover with the winding drum of the crane may be -actuated to declutch the Winding drum from driving, engagement with the prime mover as the boom of the crane reaches its predetermined limit position.

Yet another object of this invention is to provide a boom limit stop which -will also be capable of actuating a brake mechanism operatively associated with the winding drum util-ized to raise and lower the free end of the boom at the same time the winding drum is declutched from driving engageemnt with the prime mover of the crane.

Another object of -this invention is to provide a boom limit safety device which may be readily incorporated into the manufacture of new cranes and which may also be readily adapted to existing cranes.

A nal object of this invention to be specifically enuin accordance with the preceding objects which will conform to conventional forms of manufacture, be of simple construction and automatic in operation so as to provide a device that will be economically feasible, long lasting and is relatively trouble f-ree in operation.

'Illese together with other objects and advantages which will become subsequently apparent reside in the details of construction aud operation asmore fully hereinafter described and claimed, reference being had to the aecompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a side elevational view of a crane into which the boom limit safety device of the instant invention has been incorporated;

FIGURE 2 is an enlarged fragmentary side elevational view of the embodiment illustrated in FIGURE l;

FIGURE 3 is a fragmentary further enlarged side elevational view of the crane shown with 4the ram and fluid motor of the boom limit safety device in vertical section;

FIGURE 4 is an enlarged transverse vertical sectional view ltaken substantially upon the plane indicated by section line 4 4 of FIGURE 3; and

FIGURE 5 is an enlarged vertical transverse sectional View taken substantially upon the plane indicated by section line 5 5 of FIGURE 3.

While most crane operators have exceptional skill and aptitude for operating cranes, accidents caused by the free end of the boom of a crane swinging past its vertical position occur with alarming frequency. These acciice dents are usually caused by instances where the boom of a crane must be raised to almost its' maximum elevation. In these instances, it is sometimes difficult yfor the operator of a crane to know Iexactly the angle at which `the boom is disposed relative to the horizontal lsupport for the boom. While inclined indicators may be utilized to indicate the angle of the boom relative to the horizontal suppor-t to which it is secured, at times, a crane, and especially those which are mobile, are disposed on even ground and if the forward end of the horizontal support for the boom is inclined forwardly and upwardly, the inclined indicator for indicating the angular relationship between the boom and the horizontal support does not render an accurate reading with regard to the inclination of the iboom relative to 4the true horizontal. In such an instance, it is possible for even the most experienced crane operator `to raise the boom of the crane too and have the boom fall back- `wardly over the cab of the crane.

Referring now more specifically to the drawings, the numeral 10 lgenerally designates a crane of conventional design which includes a crawler-type carriage generally referred to by the reference numeral 14 and a cab generally referred to `by the reference numeral .16 which is pivotally secured to the crawler-type carriage for movement about a vertical axis.

'Phe cab 16 includes a main horizontal support 18 and one end of an elongated boom 20 is pivotally secured to the horizontal support 18 by means of a pivot connection 22 for rotation about an axis which is horizontal when the Vground 24 supporting the crane .10 is itself Ihorizontal.

The cab 16 includes suitable controls 26 for operating the crane 10 and a winding drum assembly 28 is provided. It is to be noted that a prime mover (not shown) is also enclosed within the cab 16 and the prime mover is drivingly connected to the winding drum assembly 28 by means of a clutch mechanism having a movable actuator 30. In addition, the winding drum assembly 28 includes a shaft portion 32 with which a brake assembly 34 is operatively associated and the actuator 30 also comprises meratedherein is to -provide a'boom limit safety device an actuator for the brake mechanism or assembly 34.

An elongated flexible tension member 36V has one end wound about the drum of the winding drum assembly 28 and the other end is voperatively connected to the upper end of the boom 20.

From FIGURE l of the drawings it may :be seen that the free end of the boom 20 may be moved between raised and lowered positions about the pivot connection 22 and it may also be observed from FIGURE I1 of the drawings that the boom 20 is disposed in a position close to a vertical position. If the free end of the boom 20 were raised further, it would approach the Vertical position and there would be danger of the boom 20 falling backwardly over the cab 16.

rI'lhe boom limit safety device of the present invention is generally designated by the reference numeral 38 and includes a spring loaded ram 4generally referred to by the reference numeral 40. The ram 40 includes a cylinder 42 provided with opposite end walls 44 and 46 and it may Ibe observed `from IFIGURE 3 of the drawings that the end Wall 44 is provided with a centrally disposed threaded :bore 48 in which there is secured a sleeve or packing gland 50 which slidably receives the piston rod 52 whose inner end is secured to a piston 54 slidable in the bore of the cylinder 42. The end wall 46 is also provided with a threaded bore 56 and an outlet neck 58 is thneadedly engaged in the bore 56. A compression spring `60 is disposed between the confronting surfaces of the end wall 46 and the piston 54 and a iiuid reservoir 62 is mounted atop the cylinder 42 and communicated therewith by means of a pair of check valves 64 and 66.

The lluid reservoir is provided with a removable closure 68 by which the supply of hydraulic duid 70 within the ram 40 may be replenished. The ram 40 is secured to the cab 16 by means of suitable fasteners 72 andthe outlet neck or nipple 58 is communicated with a similar nipple 74 which opens through a removable end wall 76 of an extensible uid motor 78 by means of a ilexible iluid conduit 80.

The uid motor 78 includes a cylinder member 82 which is closed at one end by means of the end Wall 76 and at the other end by means of an end wall 88 which has a centrally disposed threaded 4bore 90 formed therein in which there is disposed a bushing or packing gland 92 similar to packing gland 50. A piston 94 is slidably disposed in the cylinder member 84 and one end of a piston rod 96 is secured to the piston and is slidably received through the packing gland 92 and has its other end pivotally connected to an actuating lever 9S by means of a pin and slot connection 100.

An expansion spring 102 is disposed between the confronting surfaces of the piston 94 and the end wall 88 and therefore normally urges the piston 94 toward the end wall 76 whereas the expansion spring 60 normally urges the piston 54 toward the end wall 44.

In operation, as the boom 20 reaches the desired predetermined limit position of movement toward the vertical position, the abutment 104 of the -outer end of the piston rod 52 is engaged by the boom 20. Further movement of the boom 20 toward a vertical position will push the piston `54 toward the end wall 46 thereby effecting movement of the piston 94 toward the end wall 88 and extension of the piston rod 96 to pivot the actuating lever 98 in a lockwise direction as viewed in FIGURE 3 of the drawings to declutch the winding dr-um assembly 28 from the prime mover and apply the brake assembly 34 tothe shaft 32. Accordingly, it may be seen that the boom limit safety device 38 will not only declutch the winding drum mechanism or assembly 28 from the prime mover (not shown) but will also apply the brake assembly or mechanism 34. Thus, even though the winding drum mechanism 28 may be declutched from the prime mover, :further swinging movement of the boom 20 toward the What is claimed as new is as follows:

l. In combination with a support having one end of a beam pivotally secured thereto, a winding drum journalled from said support and having a tension member wound thereabout and yoperatively connected to said beam for electing swinging movement of said beam in response to rotation of said drum, clutch means operatively connected to said drum and including means adapted for driving connection with a prime mover and including a movable actuator for rendering said clutch means inoperative to transmit power from said prime mover to rotate said drum, a spring loaded ram including a closed cylinder having a piston snugly and slidably disposed therein with one end of a piston rod secured thereto whose other end projects outwardly of one closed end of said cylinder and is provided with an abutment, an extensible motor including a closed cylinder member having a piston snugly and slidably disposed therein with one lend of a piston rod secured thereto whose other end projects outwardly of one closed end of said cylinder member, means operatively connecting said other end of the last mentioned piston rod to said actuator, fluid conduit means communicating the other closed ends of said cylinder and cylinder member, hydraulic uid disposed in said fluid conduit and said other ends of said cylinder and cylinder member, and means mounting said ram on said support with said piston rod -disposed in the plane of movement of said beam and said abutment disposed for engagement with a portion of said beam spaced laterally of its axis of rotation defining a limit position of swinging movement of said beam toward said ram whereby as said abutment is engaged by said beam to move the piston of said ram, the piston of said iluid vertical position, which movement is possible by the inmotor will be moved and thereby effect movement of said actuator to declutch said winding drum.

2. The combination of claim 1 including brake means operatively associated with said drum for selectively preventing rotation of said drum, said clutch actuator also comprising an actuator for actuating said brake means in response to movement of said actuator to declutch said winding drum.

3. The combination of claim 1 wherein said ram includes fluid reservoir means communicable with said other end thereof.

4. The combination of claim 1 wherein said fluid motor includes means normally urging its piston rod toward a retracted position in said cylinder member.

References Cited, in the lile of this patent UNITED STATES PATENTS 1,301,643 Biank Apr. 22, 1919 2,840,244 Thomas lune 24, 1958 3,035,712 Nowack V V May 22, 1,962 

1. IN COMBINATION WITH A SUPPORT HAVING ONE END OF A BEAM PIVOTALLY SECURED THERETO, A WINDING DRUM JOURNALLED FROM SAID SUPPORT AND HAVING A TENSION MEMBER WOUND THEREABOUT AND OPERATIVELY CONNECTED TO SAID BEAM FOR EFFECTING SWINGING MOVEMENT OF SAID BEAM IN RESPONSE TO ROTATION OF SAID DRUM, CLUTCH MEANS OPERATIVELY CONNECTED TO SAID DRUM AND INCLUDING MEANS ADAPTED FOR DRIVING CONNECTION WITH A PRIME MOVER AND INCLUDING MOVABLE ACTUATOR FOR RENDERING SAID CLUTCH MEANS INOPERATIVE TO TRANSMIT POWER FROM SAID PRIME MOVER TO ROTATE SAID DRUM, A SPRING LOADED RAM INCLUDING A CLOSED CYLINDER HAVING A PISTON SNUGLY AND SLIDABLY DISPOSED THEREIN WITH ONE END OF A PISTON ROD SECURED THERETO WHOSE OTHER END PROJECTS OUTWARDLY OF ONE CLOSED END OF SAID CYLINDER AND IS PROVIDED WITH AN ABUTMENT, AN EXTENSIBLE MOTOR INCLUDING A CLOSED CYLINDER MEMBER HAVING A PISTON SNUGLY AND SLIDABLY DISPOSED THEREIN WITH ONE END OF A PISTON ROD SECURED THERETO WHOSE OTHER END PROJECTS OUTWARDLY OF ONE CLOSED END OF SAID CYLINDER MEMBER, MEANS OPERATIVELY CONNECTING SAID OTHER END OF THE LAST MENTIONED PISTON ROD TO SAID ACTUATOR, FLUID CONDUIT MEANS COMMUNICATING THE OTHER CLOSED ENDS OF SAID CYLINDER AND CYLINDER MEMBER, HYDRAULIC FLUID DISPOSED IN SAID FLUID CONDUIT AND SAID OTHER ENDS OF SAID CYLINDER AND CYLINDER MEMBER, AND MEANS MOUNTING SAID RAM ON SAID SUPPORT WITH SAID PISTON ROD DISPOSED IN THE PLANE OF MOVEMENT OF SAID BEAM AND SAID ABUTMENT DISPOSED FOR ENGAGEMENT WITH A PORTION OF SAID BEAM SPACED LATERALLY OF ITS AXIS OF ROTATION DEFINING A LIMIT POSITION OF SWINGING MOVEMENT OF SAID BEAM TOWARD SAID RAM, WHEREBY AS SAID ABUTMENT IS ENGAGED BY SAID BEAM TO MOVE THE POSTON OF SAID RAM. THE PISTON OF SAID FLUID MOTOR WILL BE MOVED AND THEREBY EFFECT MOVEMENT OF SAID ACTUATOR TO DECLUTCH SAID WINDING DRUM. 